Atomizing burner unit



March 23, 1965 R, A. voN LINDE 3,174,526

` A'romzmc BURNER UNIT Filed Aug. 25. 1960 2 Sherets-.Sheet 1 March 23,1965 R. A, VON LlNDE 3,174,526

ATOMIZING BURNER UNIT Filed Aug. 23, 1960 2 Sheets-Sheeh 2 ROJERTALBERI' V011/ [JA/DE ATRA/EKS United States Patent ice 3,174,526ATOMIZING BURNER UNIT Robert Albert von lLinde, Akilindastrasse 56,

Graefelting, near Munich, Germany Filed Aug. 23, 1960, Ser. No. 51,409 7Claims. (Cl. 15S--4) The present invention relates to an atomizingburner, especially for fluid fuels, provided with a burner pipe ormixing tube in which the combustion air supplied at relatively highvelocities absorbs the finely divided fuel supplied thereto andadditionally draws or sucks in hot combustion gases from a chamber inopen communication with the combustion space.

With the known burners of this general type, the atomizing nozzle is soarranged that the fluid fuel is atomized within the combustion airstream which is surrounded by a gaseous envelope consisting ofdrawn-back or suckedback combustion gases.

These combustion gases, the thermal contents of which could contributevery significantly to the rapid evaporation and preparation of the fuelmist, therefore, intermix themselves in the known prior art burners onlysubsequently with the fuel suspended in the combustion air and,therefore, can fulfill only incompletely the tasks assigned thereto. Itis true that by preheating the combustion air, the preparation of thefuel may be improved considerably; however, the heat exchangerinstallation required therefor would increase considerably the cost ofsuch an installation.

These disadvantages are avoided in the present invention by arrangingthe fuel atomizing nozzle in a prechamber, to which is supplied, inaccordance with the present invention, the part of the combustion gasestaken from the combustion chamber, and by discharging or terminatingthis prechamber in a mixing nozzle to which is admitted the combustionair. With such an arrangement, the combustion gases drawn or sucked-backto the mixing nozzle may give off the thermal contents thereof atrelatively high temperatures directly to the fuel mist whereby a veryrapid and complete evaporation and preparation of the fuel, as well asan advantageous mixture formation and therewith a very short and clearflame, i.e., a flame free of carbon black or soot, is formed.

These properties are also assured in case whenV a mixture very rich incombustible contents or constituents is supplied to the burner.Consequently, with the burner according to the present invention notonly very high combustion temperatures may be achieved, which are ofparticularly great value with industrial furnaces, for example, forsmelting or forging furnaces or the like, but also gas mixtures may beproduced thereby with equally good combustion which, by reason of thelarge contents in reducing eifective component parts form a suitablefurnace atmosphere for the heat treatment, for instance, of work tools.

Accordingly, it is an object of the present invention to provide aburner of the type mentioned hereinabove Which eliminates theaforementioned disadvantages encountered in the prior art devices andwhich additionally improves the combustion characteristics thereof.

Another object of the present invention is the provision of an atomizingburner in which the preparation of the fuel is considerably improved ina simple manner and without the necessity of relatively expensiveinstallations such as heat exchangers.

Another object of the present invention resides in the provisionof anatomizing burner arrangement in which optimum use is made of the thermalcontents of the combustion gases drawn back from the Vcombustion chamber7 into the atomizing unit so as to increase the rapidity and lquality ofthe fuel preparation.

Still another object of the present invention resides in the provisionof an atomizing burner arrangement in which an advantageous mixtureformation is assured with a minimum of impurities in the resulting flameso as to render the gas mixtures produced thereby particularly suitableas reduction-effective atmosphere for furnaces.

A further object of the present invention resides in the provision of anatomizing burner which produces a gas mixture containing relativelylarge contents in reducing components appropriate for the heat treatmentof work tools.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, four embodiments in accordance with thepresent invention and wherein:

FIGURE 1 is a cross-sectional view of a lirst embodiment of an atomizingburner in accordance with the present invention, and

FIGURES 2 through 4 are cross-sectional views, similar to FIGURE l, ofthree further modified embodiments of atomizing burners in accordancewith the present invention.

Referring now to the drawing, wherein like reference numerals are usedthroughout the various views to designate corresponding parts, and moreparticularly to the embodiment of FIGURE 1, reference numeral 16designates therein a combustion chamber which is limited at one endthereof by an annularly shaped flange 15 of a mixing tube or burner pipe17. Apertures 18 are provided within the annular ange 15 which dischargeinto an annular space 20 limited at the front end thereof by a toroidalsurface 19. The inner boundary surface of this annular space 20 isconstituted by the outer wall surface of an intermediate jacket or wall22 to which is connected the air supply pipe or conduit 21 and whichpasses over into a mixing nozzle 24 arranged concentrically to themixing tube or burner pipe 17.Y A fuel supply line 26 provided with anatomizing nozzle 25 terminates in the mixing nozzle 24. The wall 22 andthe mixing pipe 17 define therebetween an annular channel to which issupplied combustion air through the pipe connecting member 21. Thecombustion air thereby iiows about the freely exposed end surface of themixing pipe 17 into the mixing chamber formed by the pipe 17. As aresult of its ow energy, the combustion air draws in through the mixingnozzle 24 the combustion gases together with the combustible particlesof the fuel distributed and prepared therein which are present in theprechamber 20 and continuously ilow through the apertures 18 from thecombustion space 16 into the prechamber 20.`

The annular space 20 forming a prechamber is surrounded by a ceramichollow body 30 whereas the combustion chamber'l isV constituted by thehollow space of a fire-proof hollow body member 31. The casing 27 of theburner is provided with a liange 28 by means of which the burner may beso secured at the edge of the tiring aperture of a heat-consuming device(not illustrated), for example, of an industrial furnace or of a gasproducer which serves for purposes of obtaining neutral or reducinggaseous atmospheres that the combustion chamber 16 extends into thefiring space thereof.

The embodiment of FIGURE 2 distinguishes itself from the embodiment ofFIGURE l essentially by the fact that the section of the combustionchamber 16 adjoining the mixing pipe or burner tube 17 is enlargedconically. This section is formed by the hollow space of a ceramic body32. In order to supply a partial stream of com- 0 bustion gases,requiredwithin the meaning of the present invention for the mixtureformation, from the combustion chamber 16 to the apertures 18 andtherewith to annular Patented Mar. 23, 1965 prechamber space 2t), thehollow body member 32 is provided with several channels 36 which, on theone hand, terminate in the conical inner wall of the hollow body member32 and, on the other in an annular groove 37 facing the apertures 18.The combustion chamber 16 is closed ott by a hollow conical portionformed by the surrounding casing part 33 which decreases in crosssection in the direction toward the discharge aperture 35.

In the embodiment of FIGURE 3, one end each of several tubes 42 areinserted into the liange 15, and at the other end terminate anddischarge into a prechamber 40 having an end wall 41 providedl with amixing nozzle 24. The atomizing nozzle 25 is arranged with au apertureof the other end wall of this prechamber 40'. A hollow space defined bycylindrical casing 44 and an end wall 43 serves for purposes ofv guidingthe combustion air which thereby absorbs heat from the cornbustion gasessucked in through the pipes 42 out of the combustion chamber 16 and,therefore, absorbs in a preheated condition the mixture consisting offuel, mist and combustion gases. A spark plug 45 of known constructionserves thereby for purposes of igniting the mixture.

In the burner embodiment illustrated in FIGURE 4, the mixing pipe 17discharges into a conical section 32 of the combustion chamber 16. Aplurality of annularly distributed channels 36 are thereby provided inthe walls of this section 32. The channels 36 terminate in an annularcylindrical prechamber 20, the inner wall of which is constituted b ythe mixing pipe 17 and the outer wall of which is constituted by ajacket or wall 22. The wall 22 is secured at one end thereof at theannular flange and at the other end thereof is closed oft" by means ofan end wall 48 into which is inserted a connecting pipe 49' for theinsertion therein of the fuel nozzle 25. The mixing pipe 17 therebyforms-the forward portion of a chamber S0 into which extends a mixingnozzle 24 and which is in open communication by means of lateral hollowconnecting conduit portions 51 with the cylindrical hollow space 52. Theannular space 52 is thereby defined by the tiange 15, by the end wall 43and the cylinder jackets 22 and 44 which are provided with an air-supplyconnecting member 21. A tubular connecting member 53 extending in tightsealing arrangement through the tubular walls 44, 22 and 17 serves forthe support of a' spark plug 55. The hollow body section 32 consistingof ceramic material forms an inner insert for a hollow body 33terminating the combustion chamber 16.

Operation The burner in accordance with the present invention operatesas follows:

The combustion air supplied through the connecting pipe 21 ows withrelatively high velocity into the mixing pipe or burner tube 17 andproduces thereby at the orifice of the connecting portion or mixingnozzle 24 a vacuum or underpressure. Consequently, a` mixture-streamenters into the airstream which mixture-stream reaches the mixing nozzle24 from the combustion chamber 16 along the path indicated by thearrows. This mixture-stream absorbs the fuel injected from the nozzle 25in finely distributed form and `forms inthe first section of the mixingpipe` a very hot core stream which mixes completely with the combustionair only shortly ahead of the end of the mixing pipe 17. By reason ofthe fact thaty the liquid fuel is injected directly intothe hot drawnorsucked-back combustion gases, a very homogeneous, well-prepared and,therefore, also completely unobjectionably burning mixture resultstherefrom which burns even with a shortage of air with a short constantiiame without the formation of soot and carbon black, and which suppliesa mixture usable as furnace atmosphere having a high content in reducinggas particles. If the stoichiometric quantity of air, i.e., the quantityof combustion air exactly necessary for complete combustion of thesupplied fuel quantity, is supplied to the burner, there results theadvantage in accordance with the present invention that relatively highiiame temperatures may be readily attained.

The heat exchange between the sucked-back combustion gases and thecombustion air obtained through the wall 22 (FIGURE l) or through thewalls of the pipes 42 (FIGURE 3) results in keeping the temperature ofthe combustion gases within the vicinity of the atomizing nozzle 25within a limit favorable for the vaporization and preparation of thefuel mist. This is so as with excessive temperatures undesired sidereactions may occur which may lead to a cracking of the fuel and therebylead to the formation of soot, carbon black, or the like. On the otherhand, this heat exchange is effective in such a manner that thecombustion air also assumes a temperature favorable for the operation ofthe combustion process.

While have shown and described four embodiments in accordance with thepresent invention, it is understood that the same is not limited theretobut is susceptible of many changes and modifications within the spiritand scope thereof, and I, therefore, do not wish to be limited to thedetails shown and described herein, but intend to cover all such changesand modifications as are encompassed by the scope of the appendedclaims.

I claim:

1. An atomizing burner unit, especially for liquid fuels, comprisingcombustion chamber means, wall means forming prechamber means, means toenable combustion gases to pass from said combustion chamber means intoSaid:

prechamber means, mixing pipe means in communication with saidprechamber means, means for supplying combustion air at relatively highvelocities to said mixing pipe means to thereby draw-in hot combustiongases from said combustion chamber means through said prechamber meansinto said mixing pipe means, said wall means including two essentiallyconcentric wall parts surrounding said mixing pipe means constitutingtherebetween twohollow spaces disposed one about the other, of whichthe' outer space forms said prechamber means in open communication withsaid combustion chamber means and the inner space forms a part of saidmeans for supplying combustion air, a mixing nozzle portion secured tothe inner one of said two essentially concentric wall parts and incommunication with said mixing pipe means andl fuel atomizing means fordistributing finely divided fuel toward said mixing pipe means into thedrawn-in combustion gases.

2. An atomizing burner unit, especially for liquid fuels, comprisingcombustion chamber means, wall means forming prechamber meansterminating at one end thereof in mixing nozzle means and also formingmixing pipe means in communication with said mixing nozzle means, saidprechamber means being in communication near the other end thereof withsaid combustion chamber means to enable combustion gases to flowfrorn'said combustion chamber means through said prechamber means intosaid mixing nozzle means, inducting means including combustion airsupply means for supplying combustion air at relatively high velocitiesto said mixing pipe means to thereby draw-in hot combustion gases fromsaid combustion chamber means through said prechamber means into saidmixing pipe means by the iow energy in said combustion air, and fuelinjection means arranged in said prechamber means for injecting finelydivided fuel into said mixing nozzle means to be mixed therein with thedrawn-in combustion gases prior to admixture thereof with saidcombustion air, said wall means including two concentrically arrangedwall portions and a third wall portion forming said mixing pipemeans-said two lirst-mentioned Wall portionsand said third wall portionforming therebetween two hollow spaces disposed one about the other, theouter of which constitutes a portion of said prechamber means and theinner of which constitutes a portion of said combustion air supplymeans.

3. An atomizing burner unit according to claim 2,

gases, said section having an inner wall provided with channels incommunication with the prechamber means and with said combustion chambermeans.

5. An atomizing burner unit, especially for liquid fuels, comprisingcombustion chamber means, wall means forming prechamber meansterminating at one end thereof in mixing nozzle means .and also lformingmixing pipe means in communication with said mixing nozzle means, saidprechamber means being in communication near the other end thereof withsaid combustion chamber means to enable combustion gases to flow `fromsaid combustion chamber means through said prechamber means into saidmixing nozzle means, inducting means including combustion air Supplymeans for supplying combustion air at relatively high velocities to saidmixing pipe means to thereby draw-in hot combustion gases `from saidcombustion chamber means through said prechamber means into said mixingpipe means by the flow energy in said combustion air, and fuel injectionmeans arranged in said prechamber means for injecting finely dividedfuel into said mixing nozzle means to -be mixed therein with the drawnincombustion gases prior to admixture thereof with said combustion air,said wall means including a rst wall portion constituting an inner wallof said prechamber means and a second wall portion rigidly connectedwith said first wall portion and constituting said mixing nozzle means,and a .third wall portion forming said mixing pipe means and defining inconjunction with said first and second wall portions a passage formingpart of said air supply means,

said air supply means including an annular gap provided between saidsecond and third wall portions for the admission of the combustion `airinto said mixing pipe means.

6. An 4atomizing burner unit comprising a mixing section having anupstream end, a mixing nozzle disposed essentially coaxially to andpartially within said upstream end of said mixing section, a combustionsection, return conduit means extending rearwardly from said combustionsection into communication with said mixing nozzle to supply hotcombustion gases essentially equally around the periphery of said mixingnozzle, fuel atomizing means disposed essentially coaxially to saidmixing nozzle for dispersing nely divided fuel into the hot combustiongases passing through said mixing nozzle to vaporize said fue] prior toadmixture with combustion air, said upstream end of said mixing sectionbeing spaced from said mixing nozzle to provide passage meanstherebetween, and conduit means for supplying combustion air into saidpassage means for educting hot combustion gases and dispersed fuelvaporizing therein from `said mixing nozzle into said mixing section.

7. An -atomizing burner unit according to claim 6, wherein said returnconduit means include a plurality of spaced tubular members.

References Cited in the le of this patent UNITED STATES PATENTS 687,535Machlet Nov. 26, 1901 2,048,321 Carruthers et al July 21, 1936 2,701,608Johnson Feb. 8, 1955 2,722,372 Edwards Nov. 1, 1955 2,734,560 Harris etal Feb. 14, 1956 FOREIGN PATENTS 1,044,190 France June 17, 1953

1. AN ATOMIZING BURNER UNIT, ESPECIALLY FOR LIQUID FUELS, COMPRISINGCOMBUSTION CHAMBER MEANS, WALL MEANS FORMING PRECHAMBER MEANS, MEANS TOENABLE COMBUSTION GASES TO PASS FROM SAID COMBUSTION CHAMBER MEANS INTOSAID PRECHAMBER MEANS, MIXING PIPE MEANS IN COMMUNICATION WITH SAIDPRECHAMBER MEANS, MEANS FOR SUPPLYING COMBUSTION AIR AT RELATIVELY HIGHVELOCITIES TO SAID MIXING PIPE MEANS TO THEREBY DRAW-IN HOT COMBUSTIONGASES FROM SAID COMBUSTION CHAMBER MEANS THROUGH SAID PRECHAMBER MEANSINTO SAID MIXING PIPE MEANS, SAID WALL MEANS INCLUDING TWO ESSENTIALLYCONCENTRIC WALL PARTS SURROUNDING SAID MIXING PIPE MEANS CONSTITUTINGTHEREBETWEEN TWO HOLLOW SPACES DISPOSED SAID PRECHAMBER MEANS IN OPENAND OUTER SPACE FORMS SAID PRECHAMBER MEANS IN OPEN COMMUNICATION WITHSAID COMBUSTION CHAMBER MEANS AND IN INNER SPACE FORMS A PART OF SAIDMEANS FOR SUPPLYING COMBUSTION AIR, A MIXING NOZZLE PORTION SECURED TOTHE INNER ONE OF SAID TWO ESSENTIALLY CONCENTRIC WALL PARTS AND INCOMMUNICATION WITH SAID MIXING PIPE MEANS AND FUEL ATOMIZING MEANS FORDISTRIBUTING FINELY DIVIDED FUEL TOWARD SAID MIXING PIPE MEANS INTO THEDRAWN-IN COMBUSTION GASES.